A glass substrate is required to have not only antireflection function (a low reflectance and a high transmittance) but also other functions (e.g. ultraviolet shielding, infrared shielding, antistatic, photocatalyst, wavelength conversion) in some cases depending upon the application. For example, for a cover glass for a solar cell, an antireflection function is required to improve the power generation efficiency and in addition, an ultraviolet shielding function is required to suppress deterioration in the interior by ultraviolet light.
To prepare a film having a heat ray reflection function on a glass substrate at high temperature, a method of spraying a coating liquid containing an organic titanium compound and an organic silicon compound over a glass substrate at high temperature to form a silicon oxide-containing titanium oxide film on the glass substrate by thermal decomposition has been known (Patent Document 1).